Offset Correction For Non Horizontal Installations - Delta-T Devices SWT5 User Manual

8. Connect the signal cables as described in the chapter "Connecting
the SWT5 or SWT5x" on page 19.
9. Write down the serial number, position, installation angle and
depth.
10. Protect the cables against rodent damage. Lead the cables
through plastic pipes or protective cable trunking.
3.3

Offset correction for non horizontal installations

3 mm
Compensate the offset:

by calculation,

by entering the installation angle in the SWT-MR (Infield7) for spot
readings,

in the configuration of a data logger by setting an offset.
The deviation is largest for a vertical water column (at 0
column drawing on the pressure transducer is equal to the shaft length,
ranging from 2 to 20 cm. The offset is shifted for 0.1 kPa per cm shaft
length.
Example: A 5 cm vertical column of water below the pressure sensor
will create an 0.5 kPa offset. This means that when the soil water
tension is 0 kPa the sensor will indicate -0.5 kPa.
18  Installation
Centre of pressure transducer
The pressure transducer is calibrated without a
cup. Thus, no compensation is required for
horizontal installations.
If a SWT5 or SWT5x is installed in a non
horizontal position, the vertical water column
draws on the pressure sensor and causes an
offset shift.
Centre of ceramic
o
). The water
SWT5 User Manual v2